Use a local OneSignal SDK .aar file with Android Studio

README.MD

Using a local onesignal.aar file

1. Create a libs folder under the app directory in your project.
2. Place onesignal.aar in the newly created app/libs directory.
3. Open your project's root build.gradle file and add the folowing under repositories {...}.

flatDir {
  dirs 'libs'
}

4. Open your app/build.gradle.
5. Replace implementation 'com.onesignal:OneSignal:[3.14.0, 3.99.99]' with implementation(name: 'onesignal', ext: 'aar').
6. Add required AndroidX dependencies to your app/build.gradle

    implementation 'androidx.cardview:cardview:1.0.0'
    implementation 'androidx.fragment:fragment:1.0.0'
    implementation 'androidx.browser:browser:1.0.0'

    // OR older Android Support Libraries if you haven't migrated to AndroidX yet.
    // implementation 'com.android.support:cardview-v7:[26.0.0, 27.99.99]'
    // implementation 'com.android.support:support-fragment:[26.0.0, 27.99.99]'
    // implementation 'com.android.support:customtabs:[26.0.0, 27.99.99]'

7. Add FCM dependency if you need Google push support.

    implementation 'com.google.firebase:firebase-messaging:[10.2.1, 17.3.99]'

See the below .gradle files for full examples of the changes.

build(app).gradle

apply plugin: 'com.android.application'

android {
    compileSdkVersion 28
    buildToolsVersion '28.0.3'

    defaultConfig {
        applicationId "com.onesignal.example"
        manifestPlaceholders = [onesignal_app_id: 'b2f7f966-d8cc-11e4-bed1-df8f05be55ba',
                                onesignal_google_project_number: 'REMOTE']
        minSdkVersion 17
        targetSdkVersion 28
        versionCode 1
        versionName '1.0'
    }
}

dependencies {
    implementation fileTree(dir: 'libs', include: ['*.jar'])

    // *** NEW ***
    // Replaces compile 'com.onesignal:OneSignal:[3.14.0, 3.99.99]'
    implementation(name: 'onesignal', ext: 'aar')
    
    // *** NEW ***
    // Add `androidx` OR `com.android.support` dependencies
    // AndroidX -If you have upgrade to this already
    implementation 'androidx.cardview:cardview:1.0.0'
    implementation 'androidx.fragment:fragment:1.0.0'
    implementation 'androidx.browser:browser:1.0.0'

    // OR older Android Support Libraries if you haven't migrated to AndroidX yet.
    // implementation 'com.android.support:cardview-v7:[26.0.0, 27.99.99]'
    // implementation 'com.android.support:support-fragment:[26.0.0, 27.99.99]'
    // implementation 'com.android.support:customtabs:[26.0.0, 27.99.99]'
}

build(project).gradle

// This the root build.gradle file in your project

// Top-level build file where you can add configuration options common to all sub-projects/modules.

buildscript {
    repositories {
        google()
        jcenter()
    }
    dependencies {
        classpath 'com.android.tools.build:gradle:3.6.3'
    }
}

allprojects {
   repositories {
      google()
      jcenter()
      // *** NEW ***
      // `flatDir` section
      flatDir {
        dirs 'libs'
      }
   }
}

I followed these instructions but build was failing. Changing compile(name: 'OneSignal-release', ext: 'aar') to compile(name: 'onesignal-release', ext: 'aar') fixed it. It is probably because of the fact that your SDK's filename is onesignal-release.aar instead of OneSignal-release.aar. Please test and update the instructions.

@thetanuj Thanks for the report, I updated the instructions and example file.